[wolf1043]

Cold weather woes: Glow plugs and the EGR valve

My 2008 ML320cdi was running great until I took it to the dealer a few weeks ago for a ball joint, rear springs and brakes. Now everything seems to be going to hell. I don't know if it's all a coincidence, but sometimes I wonder if they sabotaged it to get me to come back and spend more money!

Anyway, my code reader is showing four codes:
P0671 - cylinder 1 glow plug
P1402 - EGR valve may be gunked up
P0638 - Throttle Actuator Control Range/Performance Bank 1
C0300 - Misfire

EDIT: I believe the throttle actuator and misfire codes were being caused by extremely rough starts on account of the borked glow plug.

So I went and tested all my glow plugs, voltage test and continuity test, and they all checked out fine. I removed glow plug #1 and tested it... checked out fine... but replaced it anyway and I still get the code after clearing it with my reader.

Anyway, I haven't looked at the EGR problem yet 'cuz it looks like that valve is buried at the back of the engine. I'm waiting for warmer temperatures to come around outside before I take it off to see if it's built up with carbon.

I should mention that it has become more difficult to start lately due to the cold weather (-30C), and I didn't have this problem before. Saturday evening, after sitting in the driveway for a full 24 hours in -20C temps, it wouldn't start. I wore the battery down a couple times trying to start it and had to bust out the battery charger. Finally, after charging back up for a couple hours, I was able to coax the engine to life and let it run and heat up for a couple more hours.

Any help or advice would be very much appreciated! :bowdown:

 

[wolf1043]

I tackled the EGR valve tonight. I read that it's a knuckle-buster, and I would tend to agree. Certainly not an impossible job though!

I got the two bolts out easily, and then hammered along the seam with a chisel to loosen things up. Took quite a bit of work to finally get it popped out of there. I then removed the cap off the coolant tank to relieve the pressure, then removed the two coolant lines from the EGR valve. The hardest part was getting the darn valve out from in behind everything. Had to mash it up into the firewall insulation to get it outta there.

It was pretty black with carbon. I bought some of that Seafoam Spray and hosed down the valve with it, and scrubbed it with a fingernail brush, then wiped with paper towel. I sprayed a bunch of seafoam spray into the inside of the valve and let it sit and soak for half an hour. The valve ended up pretty clean looking.

I put it back in the reverse order. Had quite a fun time with those pressure clamps on the coolant hoses.

Got everything put back together and then took it out on the highway at 110kph for half an hour, as I read the valve usually kicks in after a while at highway speeds.

Still getting the code P1402... but I'm hoping it just takes a while to go away and I don't have to replace the valve.

Anyway, photos! Hopefully these are helpful to someone, as I couldn't find much online for this project myself.

The valve is visible at the back of the drivers side. There are two torx bolts holding it in place and one electrical connector.

Close up of the valve assembly.

This is what I used to get the two bolts out. The front one is easy but the back one is a bit more cramped.

Out pops the valve after some hammering and chiseling.

Battle scars from working in such a tight space.

After getting the coolant lines off and prying the valve out of the recesses of the engine compartment, I brought it indoors to have a look.

There is some carbon buildup on it but nothing too crazy. Looks like that circular part in the middle pulls in to open the valve.

I found some Seafoam Spray at Canadian Tire, advertised as being good at removing carbon, and safe for intake/exhaust systems.

Sprayed a bunch of seafoam into the inside of the valve and let it sit for half an hour.

While the valve was soaking, I checked out the hole I pulled it out of. I took a shop vac to it and sucked up some carbon dust, and then sprayed with seafoam and wiped with paper towel.

The EGR valve, all cleaned up.

I re-installed it in reverse order, with the most challenging step being re-attaching the coolant hoses. Those pressure clamps were a pain since the hoses were so short and hard to reach.

 

[SkippyJasper]

wolf1043,

Nice post and pictures. A blood-letting suggests the car didn't like being toyed with - haha.

How many km's?

Have you had the glow plug controller replaced?

The EGR valve looked OK when you removed it and much better after you cleaned it. In my view the jury is still out on when they need to be replaced.

Did you clear the codes and the P1402 reappeared?

Agree that knowledge is sparse. Sprinter forums seem helpful to me.

Skippy

 

[wolf1043]

Hey SkippyJasper,
I've got about 124,000 kms on it now. I haven't changed the glow plug controller but I think I've just now figured out my problem!

The new glow plug I got was a Bosch 0 250 403 008 (also known as 80050). It says 4.4V on the side of it, but doesn't indicate this anywhere on the box nor can I find that detail online.

The plug I replaced was an OEM NGK plug, which says 7V on it.

Soooo... as I read in another thread somewhere, there are two types of controllers for the w164, apparently with different voltages, but the parts catalogues don't recognize that.

So, I got the wrong plug. Got a proper 7 volt one on order so we'll see if that fixes things. Also getting a block heater cord... it's been cold as hell so far this winter so I think I can use all the help I can get.


Regarding the other codes I was getting, I did clear them with my reader and they stayed away for a little while until I had another rough start because of the glow plug problem.

I have the feeling once I get this glow plug issue resolved, those other codes will go away for good.

 

[20swrt]

For other folks doing this - remove the firewall insulation to get more free space. Wolf1043 - great job with the pictures. And yes, a block heater is the way to go. Personally, if I don't get it started in 5 starts - I'll give it a rest for 5-10 mins. Try turn on ignition (no crank) 3x to warm up the glow plugs. Then finally crank it up.

 

[wolf1043]

So I got that glow plug replaced with an OEM plug, and I'm still getting P0671. Still also occasionally getting P1402.

There doesn't appear to be anything wrong with glow plug #1's harness or wire. Cleaned it with deoxy stuff to make sure. So I guess the next step is replacing the glow plug control module? I don't know what else it could be.

And I have no idea why I'd be getting P1402. It only happens when it's an extremely cold start. Do these egr valves really not like the cold?

Related perhaps: My battery is 5 years old and I know it needs to be replaced soon. If I leave the key on ACC and have the radio on, the battery runs down and needs to be charged after about an hour or two. Cold starts drain the battery after two attempts. Could a lack of starting amps be causing either of these codes somehow?

Also, I did install the block heater cable, and that's making cold starts MUCH easier now! Just had to unscrew the plastic cap on it, pop the cable on there and tighten the ring down. The cable does come quite close to one of the belts, so I zip-tied everything in place to keep it as far away as possible.

 

[SkippyJasper]

Tough call on the battery. I'm in the same boat as you and plan on replacing both this summer. Too many things need good power to work well.

I'm guessing that your Ontario location is north of my Detroit one and you likely have colder weather. Have you measured the battery volts before startup and after running? The rule of thumb is 12.5 standing (overnight) and 13. after running. The dash readout is 0.5 volts lower than battery voltage.

I wonder if there is a test procedure that can be performed on the valve while it's on the bench? Does the plunger seat against anything?

Skippy

 

[20swrt]

Get a volt meter. Connect that to any of the live 12V sockets. Monitor the voltage when you put it thru "on" and finally when you start. The voltage should never drop to less than 11 volts. And you should never operate the starter more than 2 seconds (for me at least). Im curious where you live - did you park outdoors ? If indoors - what is the temperature on the console say ?

The dealership might have a better way of testing the EGR and glow plugs.

 

[willlib]

I'm in the same boat as you guys; I leave in Quebec and it was -30C last week, battery is 5 years old didn't start at that temp. I bought a additive at the dealer ( kleenflo for diesel to avoid the gel) and also plug it.

I was at the point to take off my EGR to but, if you still have the P1402 code which is the one I have, I'm hesitating to do it now. there must be a test that we can do on the erg removed to check if it's operating normally. may be apply a voltage or a vacuum on it. I think I will remove the firewall for easier access and also, I think that the hood can be lift up at 90 degrees on those car is it right?

 

[wolf1043]

Unfortunately the nearest dealer is a 4 hour drive away and is also probably the worst one in Ontario. Sudbury fine cars. Look up their reviews. In a pinch I can drive down to Traverse City, Michigan if I really need a dealer. I did just put in a call today to a local guy who apparently works on german cars, so we'll see if that pans out. Would be nice to know I'm not totally on my own!

Anyway, for anyone considering the block heater, if your car was built for Canada it'll have the heater preinstalled. You just have to buy the cable. Here's where I got mine, and it actually does include the heater too. I couldn't find *just* the cable.
2008 Mercedes ML320 Engine Block Heater - Aftermarket & Genuine OEM

I could go out and test the voltage on the battery, but based on experience I know it needs to be replaced anyway. I'll do that soon I think.

I was thinking when I took the EGR valve out, I wonder if I can hook a 12v supply up to this thing and test if it works. But I didn't want to damage it, in case it was just a carbon problem. Not sure if I want to go through taking the valve out of there again to test it - lol!

My other thought is that there is that little EGR tube I've heard can get gunked up. But since my valve was relatively clean, I don't know if that would be the issue. Also apparently the code for that tube would be 2355(002), not a P1402.

It could also be the EGR temperature sensor screwing things up? Oddly enough it's right next to the glow plug controller... I'm also having trouble with glow plugs.

Sometimes I want to go and trade this thing in and go back to Toyota! :crybaby2:

 

[willlib]

where is located that little tube?

 

[wolf1043]

Looks like it's mounted to the back of the thing the EGR valve fits in to. So it looks like it's extraordinarily hard to access... the valve was difficult enough...

 

[wolf1043]

I picked up a new battery today and currently have it charging. Of course the ML takes the largest, most expensive battery in the store! (well, almost)

Got an Exide Edge AGM battery at PartSource. For anyone else who finds this post, charging an AGM battery is different from conventional car batteries. You need a special charger that supports AGM batteries... a regular charger will overvolt the battery and kill it within a charge or two. I have a Motomaster charger from Canadian Tire that has a mode selector... conventional or maintenance free. Maintenance free will ensure the charging voltage is right for AGM. And I read the charge rate should be set to 2A, so that's what it's set to.

Hoping to swap batteries tomorrow and I'll update on how it goes.

 

[Noodles]

The battery inventory rate for the name brands around my region is so high that even an AGM will come off the shelf at 12.5 volts or a little better.

What voltage was the Exide when you got it?

 

[wolf1043]

Didn't measure it, but it had quite a bit of dust on it. Just checked it now and it's at 12.7v, so there we go.

 

[dgiturbo]

......Still also occasionally getting P1402.....And I have no idea why I'd be getting P1402. It only happens when it's an extremely cold start. Do these egr valves really not like the cold?

Related perhaps: My battery is 5 years old and I know it needs to be replaced soon. If I leave the key on ACC and have the radio on, the battery runs down and needs to be charged after about an hour or two. Cold starts drain the battery after two attempts. Could a lack of starting amps be causing either of these codes somehow?.......

Code P1402 is not a MB code, but a generic code that common readers will show. Take the vehicle to a dealer (or an indie with MB Star Diagnostic software) and have the codes read.

You will see the MB codes relate to the differential pressure sensors in the DPF seeing low voltage plausibility readings. Nothing to do with the EGR as several post here suggest. As you noticed, this mostly happened in very cold temperatures. The low voltage after repeated cranking and start up is not liked by the 2 sensors in the DPF, and they tell the ECU to set the MIL. That code can trigger a limp home condition also.

Best fix is a new powerful AGM battery if you notice slow cranking and repeated cranking attempts to start in cold temps. If happens in warm temps and good battery, then consider replacing the sensors.

 

[wolf1043]

Awesome, that's what I was thinking and hoping it was. Thanks dgiturbo! Going to swap my battery tonight now that it's finally stopped snowing and is warming up out there.

Unfortunately I'm 4 hours away from the nearest dealer so I'm mostly on my own here.

I also just ordered a new glow plug control module. Dealer wanted $310 and I found one online from a dealer in California for $150.

Important to note for anyone else shopping for a glow plug controller: this part has been superseded several times! I read on this forum that the part number is 6411532279, but the dealer said the latest part is 6429005701.

 

[20swrt]

Got an Exide Edge AGM battery at PartSource. For anyone else who finds this post, charging an AGM battery is different from conventional car batteries. You need a special charger that supports AGM batteries... a regular charger will overvolt the battery and kill it within a charge or two. I have a Motomaster charger from Canadian Tire that has a mode selector... conventional or maintenance free. Maintenance free will ensure the charging voltage is right for AGM. And I read the charge rate should be set to 2A, so that's what it's set to.

I've replaced my AGM battery also for the first time on my 2007 CDI last Summer. I never had to charge it before installing (like most batteries off the shelf). Did the Exide instructions specifically require that it be charged first ? This is my first vehicle that requires AGM - nowhere did i read on my research it had to be charged first. So far no issues after 5 months. I bought mine from Autozone.

Before i decided to buy a new battery, I tried to have the old one charged by Autozone and they declared it DOA. I hope they knew about the difference in charging these batteries. Same as you - since it was 5 years old I just assumed it was dying. Anyway, i just noticed the voltage was dropping and dropping in the last few months. The last days i used the old one - the engine almost would not turn over....so it was really time to go.

 

[wolf1043]

I just assumed the battery may need a charge as it looked like it had been sitting on the shelf for a while. Anyway, it's installed in the car now... I cleared the P1402 code and it hasn't come up again today. We'll see if it reappears in the morning when I start it up. Going down to -20C again tonight.

Hopefully once the glow plug controller arrives and I get that swapped out, that will be the end of my cold weather problems.

 

[SkippyJasper]

FWIW,
The battery I ordered came in today (Exide Edge) and I installed it. Stickers on battery indicate December 2013 build. Heavy buggers!
I had it on a charger (Ctek) for a couple of hours before installing it. Changed the little battery too.
When I turned the vehicle on it seemed to leap to life. I'm thinking the original battery was on borrowed time, but it seemed to work OK. No indicators on the dash.
Took truck for short ride, reset things and put it back on the charger. Figure it will save some wear and tear on the alternator.
Had some grunge on the negative post. I had cleaned that when we got it a year ago.
Skippy


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